Method of forming a light-emitting device

Abstract

A method of forming a light-emitting device comprises: forming patterned portions of precursor material over a substrate, the edges of the patterned portions defining sidewalls; performing a shaping control process on the patterned portions of precursor material to control the sidewall profile to reduce the angle the sidewalls of the precursor material make with the substrate to less than 15 degrees; selectively applying from solution a conductive coating onto the portions of shaped precursor material so as to form a plurality of first conducting contacts such that an upper surface of said conductive coating follows the sidewall profile of the precursor material; forming a light-emitting layer over the conductive contacts and substrate, and forming a plurality of second conducting contacts over the light-emitting layer. The precursor material may comprises an activator catalyst and the conductive coating comprises a metal selectively applied to the shaped precursor material by electroless plating.

The invention claimed is: 
     
       1. A method of forming a light-emitting device, the method comprising:
 providing a planar substrate; 
 forming patterned portions of precursor material over the substrate, the edges of the patterned portions of precursor material defining sidewalls; 
 performing a shaping control process on the patterned portions of precursor material to control the sidewall profile of the precursor material to reduce the angle the sidewalls of the precursor material make with the planar substrate to less than 15 degrees; 
 selectively applying from solution a conductive coating onto the portions of shaped precursor material so as to form a plurality of first conducting contacts such that an upper surface of said conductive coating follows the sidewall profile of the precursor material; 
 forming a light-emitting layer over the conductive contacts and substrate, and 
 forming a plurality of second conducting contacts over the light-emitting layer. 
 
     
     
       2. A method as claimed in  claim 1 , wherein the precursor material comprises a light-curable material and an activator, and the formation of the portions of precursor material comprises exposing said portions to light prior to the application of said conductive coating. 
     
     
       3. A method as claimed in  claim 2 , wherein the light-curable material comprises one of a monomer based on an acrylate functional group and a monomer based on a methacrylate functional group. 
     
     
       4. A method as claimed in  claim 1 , wherein the patterned portions of precursor material are formed by photolithography. 
     
     
       5. A method as claimed in  claim 1 , wherein the patterned portions of precursor material are formed by printing. 
     
     
       6. A method as claimed in  claim 2 , wherein the light-curable material acts as a negative photoresist and the shaping control process comprises a proximity exposure, whereby a photomask used to selectively expose said portions of precursor material is held at a distance from the substrate during said photolithography. 
     
     
       7. A method as claimed in  claim 1 , wherein the precursor material comprises an activator catalyst and the conductive coating comprises a metal selectively applied to the shaped precursor material by electroless plating. 
     
     
       8. A method as claimed in  claim 1  wherein the shaping control process comprises a reflow bake. 
     
     
       9. A method as claimed in  claim 1 , wherein the sidewall of the precursor material makes an angle with the planar substrate of less than or equal to five degrees. 
     
     
       10. A method as claimed in  claim 1 , wherein the portions of precursor material are each formed having a ratio of width to height being less than or equal to 0.007 in the plane of said sidewall profile. 
     
     
       11. A method as claimed in  claim 1 , wherein the conducting coating comprises at least one of silver, copper, nickel, gold and Ni:P. 
     
     
       12. A method as claimed in  claim 1 , wherein the light-emitting layer comprises an electroluminescent organic material.